SUMMARY for the Mass Spectrometry and Proteomics Core Developments in mass spectrometry, primarily electrospray ionization (ESI) liquid chromatography-mass spectrometry (LCMS) with tandem mass spectrometry (MS/MS) has powered the remarkable growth in the fields of both proteomics and metabolomics. Because proteomics and metabolomics measure the dynamic state of cells and animals, they are powerful techniques for studying and discovering mechanisms for a range of pathophysiologic states from cancer to immunology. The primary goal of the Mass Spectrometry and Proteomics Core is to provide VCIID-COBRE investigators with support for experiments based on mass spectrometry-based analyses in the areas of proteomics and metabolomics. We provide support for experimental design, sample preparation, data acquisition, data analysis, and interpretation of data obtained. Services include proteomic analyses with a focus on quantification of proteins and posttranslational modifications, small molecule quantification, metabolite pattern identification, and measurement of rates and kinetics using stable isotopes of both metabolites and proteins. These services are based upon over 40 years of experience in these areas leading core facilities by the Core Director, Dr. Matthews. The Mass Spectrometry and Proteomics Core has been pivotal to the success of VCIID-COBRE faculty by contributing critical information for publications and grants during Phases I and II of the VCIID-COBRE program. With instrumentation expansion at the end of Phase II with the addition of a high resolution Waters Xevo G2-XS ESI-LCMS/MS quadrupole-time of flight instrument and Waters nanoAcquity UPLC, the Core has been able to expand its capabilities and services going into Phase III. The aims of the Core for Phase III are (1) to provide state-of-the-art mass spectrometry, cutting-edge techniques, and experienced personnel to enhance the research of the VCIID-COBRE. In addition to the standard protein analyses already conducted, VCIID-COBRE faculty has identified new techniques that are required for their future investigations. These include development of a broad-based platform for metabolomics measurements and measurement of metabolite kinetics and pathways using stable isotopically labeled tracers and broadening our capabilities to provide identification and quantification using stable isotope labels of difficult to define posttranslational modifications and rates of protein turnover. (2) To provide an infrastructure of consultative services to VCIID-COBRE faculty in the design, conduct, and interpretation of experiments to facilitate their research and (3) To develop a long- term plan for sustainability through expansion of user base with a fee-for-service structure, strong institutional support, and adaptation to changes in research needs.